The development of "integrative health care" (IHC) settings combining various aspects of Western biomedicine and complementary/alternative medicine (CAM) is a relatively recent phenomenon among biomedical and CAM professions. While IHC is recognised internationally and occurs in many different contexts (e.g. clinic or hospital), patterns of interaction between biomedical and CAM practitioners, and the nature of IHC settings, are largely unknown. This paper presents findings from a research study of two newly established IHC settings in Canada. The main research question was: how are biomedical and CAM practitioners integrating or not integrating with each other at the level of professional interaction in IHC settings? Using a case study design, in-depth interviews were conducted with 13 biomedical and eight CAM practitioners during 2002-2003, and ethnographic observation and document analysis was conducted at each site. Drawing from closure theory of the professions, comparative analysis of the sites revealed that biomedical practitioners enact patterns of exclusionary and demarcationary closure, in addition to the use of "esoteric knowledge", by: (a) dominating patient charting, referrals and diagnostic tests; (b) regulating CAM practitioners to a specific "sphere of competence"; (c) appropriating certain CAM techniques from less powerful CAM professions; and (d) using biomedical language as the primary mode of communication. CAM practitioners, in turn, perform usurpationary closure strategies, by: (a) employing their own "esoteric knowledge" in relation to biomedicine and other CAM professions; (b) appropriating biomedical language and terminology; (c) increasing their professional status by working with biomedicine; and (d) referring among CAM practitioners to increase patient flow. The findings suggest that when attempts are made to integrate biomedicine and CAM, dominant biomedical patterns of professional interaction continue to exist. Despite continued patterns of social closure, biomedical and CAM practitioners continue to provide a certain form of integrative care that may be of benefit to patients, albeit not as integrative as current models of integration would prefer.